Waveguide avalanche photodetector using quantum-dot superlattice for optical fiber communications

We report a 1.5-μm high-responsivity waveguide quantum dot photodetector with an avalanche multiplication effect and high frequency response. With two different QD layer conditions, the responsivity and avalanche multiplication were compared and discussed. The high responsivity of 0.58 A/W and avalanche multiplication factor of around 10 could be obtained. Then, it was inferred that the impact ionization process in the quantum dot superlattice would be created in the depletion layer region, not in the InGaAlAs SL region.